editor: building rotation, alt-click single wall, world-grid alignment, tap-to-engage move

[sudhir9297]

What does this PR do?

A batch of editor improvements and architectural cleanups landing the fix/mon-jun-8 line of work:

• Alt-click single wall placement. Holding Alt on the click that finishes a wall commits a single segment and clears the draft instead of chaining off the new endpoint. No-Alt remains continuous. Wired in both the 3D wall tool and the 2D floor-plan placement hook.
• Building rotation polish. Drops the 15° step button on the floating building action menu and the building-pivot helper that only existed to support it. Selected-group rotate handle remains the way to rotate a building. Earlier in the branch: consistent rotation pivot + 2D position sync, and a revert of drag-rotate / building-XZ grid chasing that proved unstable.
• Tap-to-engage 3D move grip. The 3D translate handle now hands the node to the registry move tool — the same path the floating-menu Move button takes via engageMove. One move flow drives both entry points: green bounding box, cursor follow, alignment guides, R/T rotation, click-to-commit. Adds a generic dragBounds capability on the node registry; elevator and stair opt in so the bounding box wraps just the shaft / footprint instead of the full mesh tree.
• 2D alignment in building-local frame + world-grid wall snap. The 2D alignment-guide layer now mounts inside the rotated scene <g> and reads from an editor-local store; the 3D pipeline keeps its own world-frame store. Pill labels counter-rotate so they stay upright under building rotation. Wall drafting picks up an optional gridSnap override so drafts land on the visible world-XZ grid even when the active building is rotated. Earlier on the branch: world-frame alignment guides and an upright floor-plan text geometry.
• Roof / ridge / column / shelf placement polish. Roof outer silhouette contributes to alignment-guide candidates. Ridge vent locks to its segment ridge during placement and follows live overrides afterwards. Column and shelf preview a cursor sphere during placement.
• Architecture review fix-ups. Drops a dead onRotate slot on NodeActionMenu, and memoizes the dragBounds snapshot in MoveRegistryNodeTool so it captures useScene once per node at drag-start instead of reading every render.

How to test

1. bun dev and open the editor.
2. Wall placement — start the wall tool, click once, move the cursor, click a second time with Alt held: a single wall lands and the next click starts a fresh segment. Without Alt, clicking continues to chain segments. Verify in both 3D and the 2D floor-plan panel.
3. Building rotation — select a building and rotate it via the group rotate handle. Confirm the floating action menu no longer shows a rotate button, only Move. The selected-group rotate handle should still work and the building should not drift across rotations.
4. 2D alignment under building rotation — rotate a building, then move an item / wall / slab in the 2D floor-plan. Red alignment guides should follow the rotated scene; distance pills should stay upright. Wall drafts should snap to the visible world-axis grid lines, not the building-local grid.
5. 3D move grip — select an elevator (or stair), click the move-cross gizmo: it should hand control to the registry move tool (green bounding box wrapping the shaft / footprint). Same flow as clicking Move in the floating action menu.
6. Misc placements — drop a column and a shelf: cursor sphere preview should appear during placement. Place a roof + ridge vent: the vent should lock to the ridge during placement and respond to live segment edits after.
7. bun check-types — should pass.

Screenshots / screen recording

N/A — primarily interactive behavior; will add a recording on request.

Checklist

• I've tested this locally with bun dev
• My code follows the existing code style (run bun check to verify)
• I've updated relevant documentation (if applicable)
• This PR targets the main branch